The determination of trace amounts of zinc, cadmium, lead and copper in airborne particulate matter by anodic stripping voltammetry

The application of anodic stripping voltammetry, with a hanging mercury drop electrode, to the determination of zinc, cadmium, lead and copper in airborne particulate matter collected by filtration is discussed. This procedure allows for the destruction of the filter material followed by the complete dissolution (including silicates) of the collected particulate matter. A low-temperature ashing process is described and the recovery of cadmium in this procedure is studied. Analytical data obtained by anodic stripping and atomic absorption for zinc, cadmium, lead and copper are compared.     

Sorption of copper by suspended particulate matter

The sorption of copper by suspended particulate matter from river water was investigated as a function of pH and solids concentration. Water was collected from the Delaware River and particulate matter was concentrated using Tangential-Flow Filtration (TFF). The adsorption of copper increased with increasing pH until pH 9.0. A decrease in copper adsorption was found for higher pH values. The adsorption of copper was greater for the samples with added copper than for the suspension for which no metal was added. An increase of copper adsorption proportional to particulate matter concentration was also observed. At both pH 6.0 and 7.0, there was a decrease in the adsorption of copper with increasing copper concentration.     

The determination of cadmium,copper, iron,lead and zinc in aerosols by atomic-absorption spectrometry

The determination of five elements in filter papers loaded with air particulate matter has been investigated. After a wet destruction of about 10 cm² of filter material by a standard procedure, analysis was carried out with a flame atomic absorption method for zinc and a flameless procedure for Cd, Cu, Fe and Pb. Furnace program parameters for each of the elements in different acid solutions are reported. The interferences of some common anions and the most abundant cations in aerosol material are described. For some urban and industrial samples, the results are compared with those obtained by energy-dispersive x-ray fluorescence. Accuracy was checked against standard samples.     

The determination of copper,lead, cadmium and zinc in human teeth by anodic stripping voltammetry

Differential pulse anodic stripping voltamrnetry and a hanging mercury drop electrode are used for the determination of copper, lead, cadmium and zinc in Norwegian teeth and pure hydroxyapatite. Special attention is given to the choice of decomposition procedure and the determination of the blank values. A complete dissolution of the tooth material and satisfactory blank values can be obtained by using decomposition with nitric acid in a Teflon bomb.     

Simultaneous spectrophotometric determination of cadmium, copper and zinc

A method for the simultaneous spectrophotometric determination of cadmium, copper and zinc based on the formation of their complexes with 1,5-bis(di-2-pyridylmethylene)thiocarbonohydrazide is proposed. The absorption curves of these complexes overlap severely in the scanning range 380–480 nm. The analyte concentrations are calculated by a least squares fit of the pure spectra to the mixture spectra. A linear determination range of 0.1–1.7 μg/ml for cadmium, 0.1–1.3 μg/ml for copper and 0.2–1.2 μg/ml for zinc were obtained. The effect of interference was studied. The method has been applied to the determination of these metal ions in various type of materials.     

Computerized potentiometric stripping analysis for the determination of cadmium,lead, copper and zinc in biological materials

Two different types of tinned mussels and a bovine liver reference sample have been analyzed for Zn, Cd, Pb and Cu by means of computerized potentiometric stripping analysis and atomic absorption spectrometry. The samples were digested by two different procedures, one employing nitric acid only and the other employing nitric and perchloric acids. It is shown that computerized stripping analysis can be used in samples containing high concentrations of electroactive organic nitro compounds, without sample deoxygenation.     

Enzymatic determination of cadmium,zinc, and lead in plant materials

Prospects are outlined for using the following enzymes (native and immobilized on polyurethane foam) in the rapid and highly sensitive determination of cadmium, zinc, and lead ions in plant materials (wild grass, fresh pea, and grape): horseradish peroxidase and alkaline phosphatases isolated from chicken intestine and Greenland seal small intestine. The analytical ranges of the above metals are 1 × 10^–3?25, 7 × 10^?3?250, and 3 × 10^?2?67 mg/kg dry matter, respectively. The enzymatic determination procedures developed are based on the inhibiting effect of metal ions on the catalytic activity of peroxidase in the oxidation of o-dianisidine with hydrogen peroxide and alkaline phosphatases in the hydrolysis of p-nitrophenyl phosphate. The rates of enzymatic reactions were monitored spectrophotometrically or visually. In the analysis of plant extracts, their high acidity was diminished by choosing optimum dilution factors and pH values for test samples and the nature and concentration of a buffer solution. The interference of iron(III) was removed by introducing a 0.1 M tartaric acid solution into the indicator reaction. The accuracy of the results of the enzymatic determination of cadmium, zinc, and lead in plant materials was supported by atomic absorption spectrometry and anodic stripping voltammetry.     

Electrochemical stripping determination of traces of copper, lead, cadmium and zinc in zirconium metal and zirconium dioxide

Procedures have been developed for the determination of copper, lead, cadmium and zinc in zirconium metal and zirconium dioxide, at concentrations of 1 ppm or less. Zirconium metal was dissolved in suphuric acid, and zirconium dioxide decomposed under pressure with hydrofluoric acid. Sample solutions were prepared in dilute sulphuric acid. For the stripping determination, the sample solution was either mixed with a complexing tartrate base electrolyte or the pre-electrolysis was carried out in acid solution, with the acid solution being exchanged for a pure base electrolyte (e.g. an acetate buffer) for the stripping step. The stripping step was monitored by d.c., differential pulse and Kalousek commutator voltammetry and the three methods were compared. A stationary mercury-drop electrode can generally be used for all the methods, whereas a mercury-film electrode is suitable only for the d.c. voltammetric determination of copper, lead and cadmium, as pulse measurements with films are poorly reproducible and the electrodes are easily damaged. The relative standard deviation does not exceed 20%. Some samples contained relatively large amounts of copper, which is best separated by electrodeposition on a platinum electrode.     

Simultaneous determination of lead,copper, cadmium and zinc in pure zirconium metal by differential-pulse anodic stripping voltammetry

Zirconium metal (ca. I g) was dissolved in hydrofluoric acid, excess of which was removed by fuming with sulphuric acid. An aliquot of this solution was treated with sodium citrate and adjusted to pH 4.5. Lead, copper and cadmium were deposited on the hanging mercury drop electrode by applying a potential of ?0.8 V vs. Ag/AgCl for 1 min and anodic stripping voltammograms were recorded; the anodic peaks appeared at ?0.51, ?0.14 and ?0.67 V, respectively. In a separate run, zinc was deposited at ?1.2 V and the stripping peak appeared at ?1.1 V. Standard additions were used to quantify these impurities at levels in the low mg kg^?1 range, with relative standard deviations of 5–11%.     

Direct stripping voltammetric determination of lead,cadmium and zinc dithizonates

A procedure is described in order to determine lead, cadmium and zinc dithizonates by stripping voltammetry. The polarographic analysis is performed in a medium of methanol and benzene (chloroform) in a ratio of 7:1 and in the presence of silver dithizonate. Sodium nitrate was used as a base electrolyte. By carrying out these analytic conditions it is possible to perform directly the stripping voltammetric analysis in benzene (chloroform) solution of extracted dithizonates, without further treatment. Silver nitrate in methanol is added to dithizonates in order to free lead, cadmium, and zinc from their complexes, to be determined polarographically.     

Voltammetric determination of lead,cadmium and copper traces in ammonium fluoride

A rapid and precise voltammetric method for the determination of traces of Pb, Cd and Cu in NH(4)F has been developed based on the capability of boric acid to mask fluoride ions and on the measurement of the analyte signals of the blank and the sample in the same solution.     

Voltammetric determination of lead, cadmium and copper traces in ammonium fluoride

A rapid and precise voltammetric method for the determination of traces of Pb, Cd and Cu in NH₄F has been developed based on the capability of boric acid to mask fluoride ions and on the measurement of the analyte signals of the blank and the sample in the same solution.     

Inverse-voltammetric determination of cadmium, lead and copper in animal samples after solubilization

Summary The conditions for the inverse-voltammetric determination of cadmium, lead, and copper in various biological samples after solubilization with Texapon are described. The results of this procedure are compared with those obtained with conventional high- and low-pressure wet digestions. The advantages of the Hg-film electrode as compared to the stationary Hg-electrode are discussed.Dedicated to Prof. Dr. G. Schulze on the occasion of his 60th birthday Permanent address: Technical University of Poznan, Institute of Chemistry, Poznan, Poland     

The determination of zinc,cadmium, lead and copper in a single sea-water sample by differential pulse anodic stripping voltammetry

A comparative study is described of the anodic stripping voltammetry of sea water at its natural pH and at acetate-buffered pH, with a mercury film electrode. The reproducibility of the oxidation current peaks for copper and lead is improved and the electrode memory effect decreases, when the sample is acetate-buffered (pH 5.8). Determinations of zinc at the natural pH of sea water are inaccurate, because of the formation of Zn—Cu and Zn—Ni intermetallic compounds in the mercury film. The formation of such compounds can be prevented by the addition of gallium ions to acetate-buffered samples. A procedure for the determination of Cu, Pb, Cd and Zn in sea water is described.     

Potentiometric stripping analysis for zinc,cadmium. lead and copper in sea water

Analytical procedures for the determination of zinc(II), cadmium (II), lead(II) and copper(II) in sea water by potentiometric stripping analysis are described. The results are compared with those obtained by a combined solvent extraction-atomic absorption method both in the laboratory and on-board ship. The detection limits for zinc, cadmium, lead and copper are 0.03, 0.03, 0.01 and 0.02 μg l^-1, respectively, for a total analysis time of about 75 min. A very thin mercury film is useful in the determination of lead and copper.     

Radiochemical determination of mercury,arsenic, cadmium,zinc and copper in biological materials

Extraction procedure for mercury, arsenic, cadmium, copper and zinc in biological materials is proposed. Mercury and copper are extracted with dithizone followed by the separation of mercury with tri-octyl-amine (TOA). Arsenic, cadmium and zinc are extracted as diethyldithiocarbamates. The procedure is applied for the analysis of some reference materials and autopsy human samples of kidneys, liver, heart, spleen and hair.     

Atomic absorption spectrometric determination of copper,zinc, and lead in geological materials

An atomic absorption spectrometric method is described for the determination of copper, zinc, and lead in geological materials. The sample is digested with HF—HCl—H₂O₂; the final solution for analysis is in 10 % (v/v) HCl. Copper and zinc are determined directly by aspirating the solution into an air—acetylene flame. A separate aliquot of the solution is used for determination of lead; lead is extracted into TOPO-MIBK from the acidic solution in the presence of iodide and ascorbic acid. For a 0.50-g sample, the limits of determination are 10–2000 p.p.m. for Cu and Zn, and 5–5000 p.p.m. for Pb. As much as 40 % Fe or Ca. and 10 % Al, Mg, or Mn in the sample do not interfere. The proposed method can be applied to the determination of copper, zinc, and lead in a wide range of geological materials including iron- and manganese-rich, calcareous and carbonate samples.